Zyxel Multiple Firewalls Path Traversal
CVE-2024-11667 is a critical-severity improper limitation of a pathname to a restricted directory vulnerability in ATP series firmware from Zyxel, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected ATP series firmware versions: versions V5.00 through V5.38. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on December 3, 2024, which means attacks have been observed in the wild, including in ransomware campaigns.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update usg_flex_50w_firmware to 5.38 or a later version.
- CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- Read the advisory on zyxel.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zyxel | ATP series firmware | versions V5.00 through V5.38 | Not stated |
| Zyxel | USG FLEX series firmware | versions V5.00 through V5.38 | Not stated |
| Zyxel | USG FLEX 50(W) series firmware | versions V5.10 through V5.38 | Not stated |
| Zyxel | USG20(W)-VPN series firmware | versions V5.10 through V5.38 | Not stated |
| Zyxel | usg_flex_firmware | 5.00 through 5.38 | Not stated |
| Zyxel | atp_firmware | 5.00 through 5.38 | Not stated |
| Zyxel | usg20-vpn_firmware | 5.10 through 5.38 | Not stated |
| Zyxel | usg_flex_50w_firmware | 5.10 up to, but not including, 5.38 | 5.38 |
| Zyxel | Zld | 5.00 through 5.38; 5.10 through 5.38 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.5 | High | CNA (zyxel.com.tw) |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
A directory traversal vulnerability in the web management interface of Zyxel ATP series firmware versions V5.00 through V5.38, USG FLEX series firmware versions V5.00 through V5.38, USG FLEX 50(W) series firmware versions V5.10 through V5.38, and USG20(W)-VPN series firmware versions V5.10 through V5.38 could allow an attacker to download or upload files via a crafted URL.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Limitation of a Pathname to a Restricted Directory
The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
How developers prevent this class of flaw
- For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
- Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth.
More Improper Limitation of a Pathname to a Restricted Directory vulnerabilities (CWE-22)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: partial).
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2024-11667US Government Resource
Other vulnerabilities in ATP series firmware
- 7.2 High severity
- 7.2 High severity
- 8.1 High severity
- 7.2 High severity
- 7.2 High severity
- 7.2 High severity
Recent Improper Limitation of a Pathname to a Restricted Directory vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 9.1 Critical severity
- 9.8 Critical severity
- 7.5 High severity
- 7.8 High severity
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